Industrial gas burner



July 18, 1961 J. B. HENWOOD INDUSTRIAL GAS BURNER Filed July 10, 195'?INVENTOR. JAMES B. HENWOOD BY XwdMM ATTORNEY.

Unite States Patent Pennsylvania Filed July 10, 1957, Ser. No. 670,949 6Claims. (Cl. 158-113) The present invention relates to industrial gasburners, and more particularly to a burner of this type which has builtinto it means for preheating the combustion air.

It is customary in many cases to use recuperators of one type or anotherto preheat the combustion air used in furnace burners. In all systems ofwhich I am aware, the air for all burners is heated at a central point,and is then distributed to the various burners. An arrangement of thistype requires a large amount of insulated piping which is both expensiveand bulky.

It is an object of this invention to provide means for preheating theair for individual burners. It is a further object of the invention towithdraw heated products of combustion directly from a furnace and topass them through a burner to preheat air being supplied to that burner.

It is a further, and more specific, object of the invention to provide aburner that is so constructed that products of combustion in a furnaceare withdrawn through the burner in heat exchange relation withcombustion air that is being supplied through the burner,

In carrying out the invention, gas and air are supplied throughconcentric tubes to be discharged in a substantially radial direction ina cup-shaped cavity formed in a burner block. The gas and air mix asthey are discharged into the cavity and burn along its surface to heatthe same to incandescence. Hot products of combustion forming theatmosphere of a furnace chamber, in the wall of which the burner blockis placed, have a natural in volute pattern to the center of the gas andair discharge. These products of combustion are withdrawn through thecenter of the gas and air tubes and in heat exchange relation therewith.Preferably some means is provided to control the withdrawal of theproducts of combustion through the burner tubes, and thereby the degreeof preheat that is obtained.

It is, therefore, a further object of the invention to provide furnaceburners in which the amount of preheat for the air may be controlledindividually for each burner used in a furnace.

The various features of novelty which characterize my invention arepointed out with particularity in the claims annexed to and forming apart of this specification. For

a better understanding of the invention, however, its ad- Referring tothe drawings, there is shown a refractory block 1 of high temperatureceramic material that is built into a furnace wall and forms a portionthereof. This block is provided on its furnace face with a cup ordepression 2 that has concentric with its base an opening 3 extendingthrough the block. This opening forms a continuation of an opening thatis provided through the remainder of the furnace wall in which the blockis set. A fuel and air distributor member 4 extends through the2,992,676 Patented July 18, 1961 opening provided in the furnace walland may be of any length depending upon the thickness of this wall. Theend of the distributor is received snugly in, and extends substantiallyto, the end of opening 3 with the end of the distributor projectingslightly into the base of the depression, as best shown in the drawing.

Distributor 4 includes a plurality of concentric tubes 5, 6 and 7. It isnoted that the inner tube 7 has a plurality of radially extending heatexchange ribs 8 projecting from a portion of the length thereof. Outertube 5 is provided at its left, or inner end, with a flange 9 extendingradially inward therefrom, and the flange has a plurality of openings 11forming discharge orifices drilled in it. These openings extend radiallyand at an angle to the axis of the tube. The outer or right end of tube5 is provided with a threaded inlet opening 12 and a radially extendingflange 13. Outer tube 5 is fastened to center tube 6 by means of bolts14 which extend through flange 13 and a second flange 15 that issuitably welded to the surface of tube 6. It is noted that a gasket 16is used between the two flanges in order to form a gas tight connection,since space 17 between tubes 5 and 6 is the gas passage of the burner.

Central tube 6 has attached to its inner end by a set screw 20 or othersuitable means, a hollow cylindrical member 18 that is provided on itsouter surface with a plurality of helically extending ribs 19. Thespaces be tween these ribs form helical air passages 21 through whichair is discharged into the burner cup. The outer end of tube 6 hassuitably attached thereto a casting 22 that is provided with a threadedinlet 23.

Center tube 7 is received concentrically in tube 6- and is supportedtherein by ribs '8 as well as by a sealing nut 24 which serves to holdthis tube in position both axially and radially, of tube 6 and casting22. A nozzle 25 extends into tube 7 and is directed rearwardly for apurpose to be described. This nozzle can be located in the restrictedthroat of a venturi-shaped insert 26 if it is so desired.

In the assembly of the burner, the inner end of tube 6 abuts against theback surface of flange 9 to form annular space 17 which communicateswith discharge openings 1'1, and these parts are held in position by theattachment between flanges 13 and 15. The distributor 4 itself issupported in any suitable manner in the opening in the furnace wall andburner block by attachments that can engage either tube 5 or casting 22.The distributor is located axially of the furnace wall and block 1 insuch a fashion that its inner end extends into the base of cup 2 asshown in the drawing. Inner tube 7 with its ribs 8 is moved against therear end of cylindrical member 18 in order to form an annular air spacebetween tubes 6 and 7 leading to the helical passages 21. It is notedthat the ribs -8 on the surface of tube 7 extend substantially to theend of tube 6 so that the air space is divided into a plurality of axialpassages communicating freely with the interior of casting 22.

In the operation of the burner, the gas is supplied throughinlet 12 tospace 17 and air is supplied through inlet 23 to casting 22. The gas andair in substantially stoichiometric proportions and under pressure flowthrough the respective passages and are discharged into cup 2. Theswirling air moving in a helical path through passages 21 is thrownradially outwardly across the surface of the cup by centrifugal forceand mixes with gas being discharged radially through ports 11. Thismixing of the gases takes place to form a combustible mixture that burnsalong the surface of the depression to heat the same to incandescence.Hot products of combustion are discharged'into the furnace chamber ofwhich the charged radially, a low pressure area is created at the centerof the distributor tip, thus causing an involution of the gases from theradially outward edges of depression 2 and the furnace chamber towardthe center of the distributor. Ordinarily these gases would becompletely recirculated helping to increase the temperature ofcombustion in a manner described in detail in Hess Patent 2,215,079. Inthis case, however, a portion of these recirculated gases is withdrawnthrough tube 7 to heat that tube. These gases can be in the range of1500 F. or above, depending upon the firing rate of the burner and thetemperature of the furnace which is being heated thereby. As the gasesare withdrawn through tube 7 they will lose heat to this tube and theheat will be picked up from fins 8 to preheat the air flowing past thesefins to passages 21. Thus the furnace atmosphere gases are used topreheat the air that is being supplied to the burner. Combustion air canbe preheated to between 500 and 1000" F., depending upon the temperatureof the furnace and the volume of the products of combustion that arewithdrawn through tube 7. Air under a suitably regulated pressure isdischarged through nozzle 25 to aspirate products of combustion throughtube 7, with the amount of products of combustion that are withdrawnthrough the tube depending to a large extent upon the velocity of theair being discharged from nozzle 25. If it is desired, the insert 26 canbe placed in pipe 7 in order to increase the efiiciency of theaspirating effect of nozzle 25.

Under some circumstances it may be desirable to temper the hot productsof combustion that are being withdrawn through tube 7. When it isnecessary to do this, tube 7 is so adjusted relative to tube 6 that someof the air supplied to the burner is withdrawn through tube 7 in orderto reduce its temperature. One means for accomplishing this is shown inFIG. 4. It will be seen by referring to that figure that the inner endof tube 7 does not engage the back of member 18 as it does in thepreviously described embodiment of the invention. This tube is alsoprovided with a reduced extension 27 that extends through the bore ofmember 18 to a point adjacent to the end thereof. It will be noted thatthe inner end of member 18 extends radially inward to a pointsubstantially overlying the end of extension 27.

This burner operates in exactly the same fashion as the previouslydescribed embodiment. In this case, however, a small portion of airbeing supplied to the burner is discharged between the inner surface ofmember 18 and the outer surface of extension 27. The air is thenwithdrawn through tube 7 along with the products of combustion to temperthese products of combustion and thereby prevent them from overheatingtube 7 and damaging the burner.

From the above description it will be seen that [I have provided anindustrial burner in which there is means to preheat the air as it isflowing through the burner. Thus, preheated air is obtained to increasethe temperature and efficiency of the furnace operation without thenecessity for a large recuperator. Furthermore, a construction of thistype does away with the necessity for a great amount of piping that isrequired to bring preheated air to a plurality of individual burnersthat are located at various points on a furnace. In addition, theconstruction shown herein permits preheating of the air to variousburners individually as required by their particular location in afurnace, the amount of preheating being determined by the velocity ofair being discharged through nozzle 25. This can be adjusted readily byan individual valve (not shown) that is used in the supply line to thenozzle.

The burner of this invention operates in the same manner as aconventional radiant cup-type burner, in that it produces a large amountof radiation as well as hot products of combustion that are directedinto a furnace chamber. The hot products of combustion must be exhaustedfrom the chamber in some fashion, and removing a portion of them throughtube 7 of the individual burners is an excellent way to preheat air. Theproducts of combustion discharged through tube 7, which are a relativelysmall proportion of the total volume of the furnace gases, may either bedischarged to the atmosphere or may be piped to a suitable flue.

While in accordance with the provisions of the statutes, I haveillustrated and described the best form of embodiment of my inventionnow known to me, it will be apparent to those skilled in the art thatchanges may be made in the form of the apparatus disclosed withoutdeparting from the spirit and scope of the invention set forth in theappended claims, and that in some cases certain features of my inventionmay be used to ad? vantage without a corresponding use of otherfeatures.

What is claimed is:

1. In a burner for use in a furnace Wall, the combination of a tubularelement having an end adapted to extend into a furnace chamber, meansforming a first annular space in said element terminating in said end ina ring of radially directed discharge orifices adjacent to the peripheryof said end, means forming a second annular space within said firstannular space terminating in said end in a plurality of helicallydirected passages located in a ring within said ring'of orifices, meansin said member forming a passage extending from said end and concentricwithin said second annular space, means to supply fuel gas to said firstmentioned annular space, means to supply combustion air to said secondannular space, and means connected with said concentric passage toWithdraw products of combustion through said concentric passage.

2. In a burner for use in a furnace wall, the combination of arefractory block having a cup-shaped depression in one surface thereofand an opening extending from the base of said depression to an oppositesurface thereof, a fuel distributor extending through said opening withan end thereof adjacent to said base, means to supply air to saiddistributor, means in said distributor to discharge the air into saiddepression in a plurality of helically directed streams, wherebycentrifugal force throws the air against the surface of said depression,means surrounding said air supply means to supply fuel gas to saiddistributor, means in the end of said distributor to direct the gas intosaid depression in a plurality of radially directed streams to mix withthe air and burn along the surface of said depression, means to withdrawproducts.

of combustion from said depression through the center of saiddistributor and means to vary the amount of products of combustionwithdrawn.

3. In a burner, an elongated tubular element vhaving an end thereofadapted to extend into a furnace, means forming a plurality ofconcentric passages in said. ele ment, means closing the end of theouter of said passages including a port formed with a plurality ofradially directed orifices, means closing the end of the next innerpassage including a port formed with a plurality of axially directedhelical channels, and' the inner. passage forming an axially directedopening, means to supply fuel gas to said outer passage, means to supplycombustion air to said next inner passage, and means in said innerpassage to withdraw products of combustion through said opening in theend of said inner passage.

4. In a burner, a distributor element having a discharge end, means insaid end to discharge fuel gas in a plurality of radially outwardlydirected streams arranged in a circle, means in said end to dischargeair in a plurality of axial and helically directed paths arranged in acircle inside said circle of gas streams, whereby centrifugal forcethrows said air stream radially outward to mix with said gas streams toform acombustiblemixture and burn, so that the outward movement of saidair and gas streams creates a low pressure area at the center of saidend, and means in said end adjacent to the point where said low pressurearea is created forming a passage extending back in said distributorelement through which products of combustion can pass, and meansconnected with said passage to withdraw products of combustion throughsaid passage.

5. In a burner for use in a furnace wall, a distributor element adaptedto extend through the wall and comprising a plurality of concentrictubes, means closing the end of the annular space between the outertubes, said means being provided with a ring of openings directedradially outwardly, means closing the end of the annular space adjacentto said first mentioned space, said last means comprising a plurality ofhelically extending ribs operative to form a plurality of passagesterminating in said end and located in a ring, said tubes forming apassage inside said second mentioned space extending to the back of saidelement, means to supply gas to the outer one of said annular spaces,means to supply air to the other of said annular spaces and means insaid passage to Withdraw products of combustion through said passage.

6. The combination of claim 5 including a plurality of radiallyprojecting ribs on the outer surface of the tube forming said passage,said ribs extending into said second annular space.

References Cited in the file of this patent UNITED STATES PATENTS 792,642 Williams June 20, 1905 1,352,351 Byers Sept. 7, 1920 1,991,894 ForneyFeb. 19, 1935 2,215,079 Hess Sept. 17, 1940 2,226,816 Hepburn Dec. 31,1940 2,547,735 Blaha Apr. 3, 1951 2,935,127 Stalego May 3, 1960 FOREIGNPATENTS 564,754 Germany Nov. 22, 1932 551,568 Great Britain Mar. 1, 1943UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.2,992,676 7 July 18, 1961 Jemes B. Henwood It is hereby certifiedtha'berror appears inn -the above numbered paten'brequiring correction andthat'the said Letters Patent should read as "corrected below.

Column 4', lines 56 and 58, for "port'fl, each occurrence read partSigned and sealed this 23rd day of January 1962.

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents

